In an image sensor, to improve photo sensitivity, either a fill factor, which is a ratio of a photodiode area to the whole area of the image sensor, is increased, or a photo-gathering technology is used to change the path of light incident onto an area other than the photodiode area such that the light can be collected in the photodiode.
When a manufacturing process of an image sensor has been completed, the image sensor is subject to a packaging process, and an external lens is attached to the image sensor.
However, according to the related art as illustrated in FIG. 1, although the image sensor does not have a problem in forming images at the center of the image sensor chip using light incident from an external lens 3, the amount of light introduced into a photodiode 2 by passing through a micro-lens 1 is gradually decreased from the center of the image sensor chip to an edge (A) of the image sensor chip.
Accordingly, as the amount of light incident onto a unit pixel is changed, the number of generated electrons changes, so that a color image formed at the center of the image sensor is different from a color image formed at the edge of the image sensor even if the color of an the original image is not changed.
Such a phenomenon, together with crosstalk to adjacent pixels, lowers reliability of the image sensor, so that light efficiency is lowered.